repl: fix crash when bare 'import' is typed

Author: WaqarNiaxi

lib/repl.js

@@ -250,7 +250,12 @@ writer.options = { ...inspect.defaultOptions, showProxy: true };
 // Converts static import statement to dynamic import statement
 const toDynamicImport = (codeLine) => {
   let dynamicImportStatement = '';
-  const ast = acornParse(codeLine, { __proto__: null, sourceType: 'module', ecmaVersion: 'latest' });
+  let ast;
+  try {
+    ast = acornParse(codeLine, { __proto__: null, sourceType: 'module', ecmaVersion: 'latest' });
+  } catch {
+    return codeLine;
+  }
   acornWalk.ancestor(ast, {
     ImportDeclaration(node) {
       const awaitDynamicImport = `await import(${JSONStringify(node.source.value)});`;

test/parallel/test-repl-import-incomplete-crash.js

@@ -0,0 +1,13 @@
+'use strict';
+const common = require('../common');
+const child_process = require('child_process');
+const assert = require('assert');
+
+// Regression test for https://github.com/nodejs/node/issues/63551:
+// Typing a bare `import` keyword in the REPL must not crash the process.
+const proc = child_process.spawn(process.execPath, ['-i']);
+proc.on('error', common.mustNotCall());
+proc.on('exit', common.mustCall((code) => {
+  assert.strictEqual(code, 0);
+}));
+proc.stdin.write('import\n.exit\n');