src,inspector: fix empty MaybeLocal crash

Return early when the Inspector StringView to V8 String conversion fails
and returns an empty MaybeLocal instead of running the invalid
ToLocalChecked() assertion.

Fixes: #42407
Signed-off-by: Darshan Sen <raisinten@gmail.com>

PR-URL: #42409
Backport--PR-URL: #42967
Reviewed-By: Richard Lau <rlau@redhat.com>
Reviewed-By: Mohammed Keyvanzadeh <mohammadkeyvanzade94@gmail.com>
Reviewed-By: Anna Henningsen <anna@addaleax.net>
Reviewed-By: Tobias Nießen <tniessen@tnie.de>
Reviewed-By: Juan José Arboleda <soyjuanarbol@gmail.com>
Reviewed-By: James M Snell <jasnell@gmail.com>

test/pummel/test-repl-empty-maybelocal-crash.js

@@ -0,0 +1,20 @@
+'use strict';
+const common = require('../common');
+
+if (process.config.variables.arm_version === '7') {
+  common.skip('Too slow for armv7 bots');
+}
+
+// The process should not crash when the REPL receives the string, 'ss'.
+// Test for https://github.com/nodejs/node/issues/42407.
+
+const repl = require('repl');
+
+const r = repl.start();
+
+r.write('var buf = Buffer.from({length:200e6},(_,i) => i%256);\n');
+r.write('var ss = buf.toString("binary");\n');
+r.write('ss');
+r.write('.');
+
+r.close();