Use instanceof checks for complex types, typeof for builtin types

Also remove unneeded null check when `result instanceof Object`
https://stackoverflow.com/questions/899574/what-is-the-difference-between-typeof-and-instanceof-and-when-should-one-be-used

test/resolveLocation.test.js

@@ -13,25 +13,25 @@ test('resolveLocation', async t => {
     await t.test('a valid [lon, lat] Array returns a feature match', t => {
       const location = [0, 0];
       const result = loco.resolveLocation(location);
-      assert.notEqual(result, null);
+      assert.ok(result instanceof Object);
       assert.equal(result.type, 'point');
       assert.equal(result.location, location);
-      assert.equal(typeof result.feature, 'object');             // result includes a `feature`
+      assert.ok(result.feature instanceof Object);               // result includes a `feature`
       assert.equal(result.feature.id, '[0,0]');                  // feature has an `id`
-      assert.equal(typeof result.feature.properties, 'object');  // feature has `properties`
+      assert.ok(result.feature.properties instanceof Object);    // feature has `properties`
       assert.equal(result.feature.properties.id, '[0,0]');       // properties has an `id` property
       assert.equal(result.feature.properties.area, 1963.5);      // area = Pi * 25 * 25
     });
 
     await t.test('a valid [lon, lat, radius] Array returns a feature match', t => {
       const location = [0, 0, 100];
       const result = loco.resolveLocation(location);
-      assert.notEqual(result, null);
+      assert.ok(result instanceof Object);
       assert.equal(result.type, 'point');
       assert.equal(result.location, location);
-      assert.equal(typeof result.feature, 'object');             // result includes a `feature`
+      assert.ok(result.feature instanceof Object);               // result includes a `feature`
       assert.equal(result.feature.id, '[0,0,100]');              // feature has an `id`
-      assert.equal(typeof result.feature.properties, 'object');  // feature has `properties`
+      assert.ok(result.feature.properties instanceof Object);    // feature has `properties`
       assert.equal(result.feature.properties.id, '[0,0,100]');   // properties has an `id` property
       assert.equal(result.feature.properties.area, 31415.93);    // area = Pi * 100 * 100
     });
@@ -52,38 +52,38 @@ test('resolveLocation', async t => {
     await t.test('a known `.geojson` filename with id returns a feature match', t => {
       const location = 'dc_metro.geojson';
       const result = loco.resolveLocation(location);
-      assert.notEqual(result, null);
+      assert.ok(result instanceof Object);
       assert.equal(result.type, 'geojson');
       assert.equal(result.location, location);
-      assert.equal(typeof result.feature, 'object');                    // result includes a `feature`
+      assert.ok(result.feature instanceof Object);                      // result includes a `feature`
       assert.equal(result.feature.id, 'dc_metro.geojson');              // feature has an `id`
-      assert.equal(typeof result.feature.properties, 'object');         // feature has `properties`
+      assert.ok(result.feature.properties instanceof Object);           // feature has `properties`
       assert.equal(result.feature.properties.id, 'dc_metro.geojson');   // properties has an `id` property
       assert.equal(typeof result.feature.properties.area, 'number');    // properties has a numeric `area` property
     });
 
     await t.test('a known `.geojson` filename with id property returns a feature match', t => {
       const location = 'philly_metro.geojson';
       const result = loco.resolveLocation(location);
-      assert.notEqual(result, null);
+      assert.ok(result instanceof Object);
       assert.equal(result.type, 'geojson');
       assert.equal(result.location, location);
-      assert.equal(typeof result.feature, 'object');                        // result includes a `feature`
+      assert.ok(result.feature instanceof Object);                          // result includes a `feature`
       assert.equal(result.feature.id, 'philly_metro.geojson');              // feature has an `id`
-      assert.equal(typeof result.feature.properties, 'object');             // feature has `properties`
+      assert.ok(result.feature.properties instanceof Object);               // feature has `properties`
       assert.equal(result.feature.properties.id, 'philly_metro.geojson');   // properties has an `id` property
       assert.equal(typeof result.feature.properties.area, 'number');        // properties has a numeric `area` property
     });
 
     await t.test('`.geojson` identifiers compare as lowercase', t => {
       const location = 'PHiLLy_MeTRo.GeoJSoN';
       const result = loco.resolveLocation(location);
-      assert.notEqual(result, null);
+      assert.ok(result instanceof Object);
       assert.equal(result.type, 'geojson');
       assert.equal(result.location, location);
-      assert.equal(typeof result.feature, 'object');                        // result includes a `feature`
+      assert.ok(result.feature instanceof Object);                          // result includes a `feature`
       assert.equal(result.feature.id, 'philly_metro.geojson');              // feature has an `id`
-      assert.equal(typeof result.feature.properties, 'object');             // feature has `properties`
+      assert.ok(result.feature.properties instanceof Object);               // feature has `properties`
       assert.equal(result.feature.properties.id, 'philly_metro.geojson');   // properties has an `id` property
       assert.equal(typeof result.feature.properties.area, 'number');        // properties has a numeric `area` property
     });
@@ -104,12 +104,12 @@ test('resolveLocation', async t => {
     await t.test('a valid country coder feature identifier returns a feature match', t => {
       const location = 'gb';
       const result = loco.resolveLocation(location);
-      assert.notEqual(result, null);
+      assert.ok(result instanceof Object);
       assert.equal(result.type, 'countrycoder');
       assert.equal(result.location, location);
-      assert.equal(typeof result.feature, 'object');                   // result includes a `feature`
+      assert.ok(result.feature instanceof Object);                     // result includes a `feature`
       assert.equal(result.feature.id, 'Q145');                         // feature has an `id`
-      assert.equal(typeof result.feature.properties, 'object');        // feature has `properties`
+      assert.ok(result.feature.properties instanceof Object);          // feature has `properties`
       assert.equal(result.feature.properties.id, 'Q145');              // properties has an `id` property
       assert.equal(typeof result.feature.properties.area, 'number');   // properties has a numeric `area` property
     });