debugger: throw debugger error when the frame is missing

lib/internal/debugger/inspect_repl.js

@@ -635,6 +635,9 @@ function createRepl(inspector) {
 
   // List source code
   function list(delta = 5) {
+    if (!selectedFrame) {
+      throw new ERR_DEBUGGER_ERROR('Requires execution to be paused');
+    }
     return selectedFrame.list(delta).then(null, (error) => {
       print("You can't list source code right now");
       throw error;

test/sequential/test-debugger-list.js

@@ -0,0 +1,35 @@
+'use strict';
+const common = require('../common');
+
+common.skipIfInspectorDisabled();
+
+const fixtures = require('../common/fixtures');
+const startCLI = require('../common/debugger');
+
+const assert = require('assert');
+
+const cli = startCLI([fixtures.path('debugger/three-lines.js')]);
+
+cli.waitForInitialBreak()
+  .then(() => cli.waitForPrompt())
+  .then(() => cli.command('list(0)'))
+  .then(() => {
+    assert.match(cli.output, /> 1 let x = 1;/);
+  })
+  .then(() => cli.command('list(1)'))
+  .then(() => {
+    assert.match(cli.output, /> 1 let x = 1;\n {2}2 x = x \+ 1;/);
+  })
+  .then(() => cli.command('list(10)'))
+  .then(() => {
+    assert.match(cli.output, /> 1 let x = 1;\n {2}2 x = x \+ 1;\n {2}3 module\.exports = x;\n {2}4 /);
+  })
+  .then(() => cli.command('c'))
+  .then(() => cli.waitFor(/disconnect/))
+  .then(() => cli.waitForPrompt())
+  .then(() => cli.command('list()'))
+  .then(() => {
+    assert.match(cli.output, /Uncaught Error \[ERR_DEBUGGER_ERROR\]: Requires execution to be paused/);
+  })
+  .finally(() => cli.quit())
+  .then(common.mustCall());