title: When I try to build the APK Following shows in the debug console. Build: Build Failed with an exception
body: <p>/C:/src/flutter/flutter/.pub-cache/hosted/pub.dartlang.org/flutter_datetime_picker-1.3.8/lib/src/datetime_picker_theme.dart:6:28: Error: Type 'DiagnosticableMixin' not found.
  class DatePickerTheme with DiagnosticableMixin {
  ^^^^^^^^^^^^^^^^^^^
  /C:/src/flutter/flutter/.pub-cache/hosted/pub.dartlang.org/flutter_svg-0.17.4/lib/src/picture_stream.dart:88:26: Error: Type 'DiagnosticableMixin' not found.
  class PictureStream with DiagnosticableMixin {
  ^^^^^^^^^^^^^^^^^^^
  /C:/src/flutter/flutter/.pub-cache/hosted/pub.dartlang.org/flutter_svg-0.17.4/lib/src/picture_stream.dart:192:44: Error: Type 'DiagnosticableMixin' not found.
  abstract class PictureStreamCompleter with DiagnosticableMixin {
  ^^^^^^^^^^^^^^^^^^^
  /C:/src/flutter/flutter/.pub-cache/hosted/pub.dartlang.org/flutter_datetime_picker-1.3.8/lib/src/datetime_picker_theme.dart:6:7: Error: The type 'DiagnosticableMixin' can't be mixed in.
  class DatePickerTheme with DiagnosticableMixin {
  ^
  /C:/src/flutter/flutter/.pub-cache/hosted/pub.dartlang.org/flutter_svg-0.17.4/lib/src/picture_stream.dart:88:7: Error: The type 'DiagnosticableMixin' can't be mixed in.
  class PictureStream with DiagnosticableMixin {
  ^
  /C:/src/flutter/flutter/.pub-cache/hosted/pub.dartlang.org/flutter_svg-0.17.4/lib/src/picture_stream.dart:192:16: Error: The type 'DiagnosticableMixin' can't be mixed in.
  abstract class PictureStreamCompleter with DiagnosticableMixin {
  ^
  /C:/src/flutter/flutter/.pub-cache/hosted/pub.dartlang.org/flutter_svg-0.17.4/lib/src/picture_stream.dart:167:11: Error: Superclass has no method named 'debugFillProperties'.
  super.debugFillProperties(properties);
  ^^^^^^^^^^^^^^^^^^^
  /C:/src/flutter/flutter/.pub-cache/hosted/pub.dartlang.org/flutter_svg-0.17.4/lib/src/picture_stream.dart:171:30: Error: The method 'toStringShort' isn't defined for the class 'PictureStreamCompleter'.</p>
  <ul>
  <li>'PictureStreamCompleter' is from 'package:flutter_svg/src/picture_stream.dart' ('/C:/src/flutter/flutter/.pub-cache/hosted/pub.dartlang.org/flutter_svg-0.17.4/lib/src/picture_stream.dart').
  Try correcting the name to the name of an existing method, or defining a method named 'toStringShort'.
  ifPresent: _completer?.toStringShort(),
  ^^^^^^^^^^^^^
  /C:/src/flutter/flutter/.pub-cache/hosted/pub.dartlang.org/flutter_svg-0.17.4/lib/src/picture_stream.dart:266:11: Error: Superclass has no method named 'debugFillProperties'.
  super.debugFillProperties(description);
  ^^^^^^^^^^^^^^^^^^^</li>
  </ul>
  <p>FAILURE: Build failed with an exception.</p>
  <ul>
  <li><p>Where:
  Script 'C:\src\flutter\flutter\packages\flutter_tools\gradle\flutter.gradle' line: 896</p>
  </li>
  <li><p>What went wrong:
  Execution failed for task ':app:compileFlutterBuildDebug'.</p>
  </li>
  </ul>
  <blockquote>
  <p>Process 'command 'C:\src\flutter\flutter\bin\flutter.bat'' finished with non-zero exit value 1</p>
  </blockquote>
  <ul>
  <li><p>Try:
  Run with --stacktrace option to get the stack trace. Run with --info or --debug option to get more log output. Run with --scan to get full insights.</p>
  </li>
  <li><p>Get more help at <a href="https://help.gradle.org" rel="noreferrer">https://help.gradle.org</a></p>
  </li>
  </ul>
  <p>BUILD FAILED in 1m 12s
  Exception: Gradle task assembleDebug failed with exit code 1
  Exited (sigterm)</p>