repl: fix crash when bare 'import' is typed

[WaqarNiaxi]

Typing a bare import keyword in the REPL followed by Enter caused
the process to crash with an uncaught SyntaxError from acorn. The
crash path was:

1. V8 evaluates import\n and throws a SyntaxError:
   "Cannot use import statement outside a module".
2. The REPL error handler calls toDynamicImport() to build a helpful
   hint message.
3. toDynamicImport() called acornParse() without a try-catch.
4. acorn threw SyntaxError: Unexpected token (1:6) because the bare
   import is not a complete import statement.
5. The uncaught error propagated synchronously back through the
   keypress event chain and was re-thrown in emitKeypressEvents:74,
   crashing the process.

Fix: wrap the acornParse() call in toDynamicImport() in a try-catch.
On parse failure, return the original codeLine unchanged so the
error message is still usable.

Fixes: #63551"

[aduh95]

Can we avoid the spawn here? Something similar to

node/test/parallel/test-repl-null.js

Lines 1 to 13 in 8c495c8

	'use strict';
	require('../common');
	const repl = require('repl');
	const replserver = new repl.REPLServer();
	replserver._inTemplateLiteral = true;
	// `null` gets treated like an empty string. (Should it? You have to do some
	// strange business to get it into the REPL. Maybe it should really throw?)
	replserver.emit('line', null);
	replserver.emit('line', '.exit');

[WaqarNiaxi]

Resolved

[codecov]

Codecov Report

✅ All modified and coverable lines are covered by tests.
✅ Project coverage is 90.30%. Comparing base (2e3daf6) to head (3e297b7).
⚠️ Report is 71 commits behind head on main.

Additional details and impacted files

@@            Coverage Diff             @@
##             main   #63552      +/-   ##
==========================================
- Coverage   90.34%   90.30%   -0.04%     
==========================================
  Files         730      730              
  Lines      234359   235482    +1123     
  Branches    43923    44387     +464     
==========================================
+ Hits       211720   212648     +928     
- Misses      14361    14631     +270     
+ Partials     8278     8203      -75     

Files with missing lines	Coverage Δ
lib/repl.js	94.03% <100.00%> (+0.01%)	⬆️

... and 203 files with indirect coverage changes

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