LSP server crashes when rename keeping the same name

[ericdallo]

Describe the bug
When renaming a symbol using lsp-rename and keeping the same name, the server crashes and lsp mode prints Server dart_analysis_server:23820 exited with status exit. Do you want to restart it? (y or n)

Version

[LSP Dart] 1.12.7 at 2020.07.04 @ Emacs 27.0.91
[Dart SDK] Dart VM version: 2.9.0-19.0.dev.flutter-7e72c9ae7e (be) (Fri Jun 19 18:05:23 2020 +0000) on "linux_x64"

lsp-log

[Trace - 04:36:07 PM] Sending request 'textDocument/prepareRename - (183)'.
Params: {
  "textDocument": {
    "uri": "file:///home/greg/dev/flutter_sample/lib/screens/dashboard/components/rightscreen.dart"
  },
  "position": {
    "line": 52,
    "character": 21
  }
}

[Trace - 04:36:07 PM] Received response 'textDocument/prepareRename - (183)' in 8ms.
Result: {
  "placeholder": "_goToNextPage",
  "range": {
    "end": {
      "character": 28,
      "line": 52
    },
    "start": {
      "character": 15,
      "line": 52
    }
  }
}

[Trace - 04:36:12 PM] Sending request 'textDocument/rename - (184)'.
Params: {
  "textDocument": {
    "uri": "file:///home/greg/dev/flutter_sample/lib/screens/dashboard/components/rightscreen.dart"
  },
  "position": {
    "line": 52,
    "character": 21
  },
  "newName": "_goToNextPage"
}

[Trace - 04:36:12 PM] Received response 'textDocument/rename - (184)' in 7ms.
Result: null

[ericdallo]

Fixed on dart sdk: dart-lang/sdk#42573 (comment)