refactor: split out a common typecheckFile func (#344)

* refactor: split out a common typecheckFile func

- this is used in 3 places and going to be more for the code I'm adding
  to fix type-only imports
  - so DRY it up and standardize the functionality too
    - some places had `noErrors = false` in one place while others had
      it in another
    - same for `printDiagnostics`
    - but the ordering actually doesn't matter, so just keep it
      consistent and the same
      - and then can split a common function that does both out

- technically, now getDiagnostics is _only_ used in typecheckFile, so
  I could link to the two together, but I'm refactoring that one up
  a little
  - but this a good, small example of how refactoring one part of a
    codebase can make it easier to identify more similar pieces and then
    refactor even more

* fix lint error on shadowed name

src/index.ts

@@ -8,7 +8,7 @@ import * as resolve from "resolve";
 import findCacheDir from "find-cache-dir";
 
 import { RollupContext } from "./rollupcontext";
-import { ConsoleContext, VerbosityLevel } from "./context";
+import { ConsoleContext, IContext, VerbosityLevel } from "./context";
 import { LanguageServiceHost } from "./host";
 import { TsCache, convertDiagnostic, convertEmitOutput, getAllReferences } from "./tscache";
 import { tsModule, setTypescriptModule } from "./tsproxy";
@@ -56,6 +56,15 @@ const typescript: PluginImpl<RPT2Options> = (options) =>
  }));
  }
 
+ const typecheckFile = (id: string, snapshot: tsTypes.IScriptSnapshot, tcContext: IContext) =>
+ {
+ const diagnostics = getDiagnostics(id, snapshot);
+ printDiagnostics(tcContext, diagnostics, parsedConfig.options.pretty === true);
+
+ if (diagnostics.length > 0)
+ noErrors = false;
+ }
+
  const pluginOptions: IOptions = Object.assign({},
  {
  check: true,
@@ -201,11 +210,8 @@ const typescript: PluginImpl<RPT2Options> = (options) =>
 
  if (output.emitSkipped)
  {
- noErrors = false;
-
  // always checking on fatal errors, even if options.check is set to false
- const diagnostics = getDiagnostics(id, snapshot);
- printDiagnostics(contextWrapper, diagnostics, parsedConfig.options.pretty === true);
+ typecheckFile(id, snapshot, contextWrapper);
 
  // since no output was generated, aborting compilation
  cache().done();
@@ -218,13 +224,7 @@ const typescript: PluginImpl<RPT2Options> = (options) =>
  });
 
  if (pluginOptions.check)
- {
- const diagnostics = getDiagnostics(id, snapshot);
- if (diagnostics.length > 0)
- noErrors = false;
-
- printDiagnostics(contextWrapper, diagnostics, parsedConfig.options.pretty === true);
- }
+ typecheckFile(id, snapshot, contextWrapper);
 
  if (!result)
  return undefined;
@@ -277,19 +277,15 @@ const typescript: PluginImpl<RPT2Options> = (options) =>
  return;
 
  const snapshot = servicesHost.getScriptSnapshot(id);
- if (!snapshot)
- return;
-
- const diagnostics = getDiagnostics(id, snapshot);
- printDiagnostics(context, diagnostics, parsedConfig.options.pretty === true);
+ if (snapshot)
+ typecheckFile(id, snapshot, context);
  });
  }
 
  if (!watchMode && !noErrors)
  context.info(yellow("there were errors or warnings."));
 
  cache().done();
-
  generateRound++;
  },