conditional breakpoint fails if String condition is set/used #782

[provide a description of the issue]

Environment

• Operating System: Windows 10 x64
• JDK version:
  openjdk version "1.8.0_242"
  OpenJDK Runtime Environment (AdoptOpenJDK)(build 1.8.0_242-b08)
  OpenJDK 64-Bit Server VM (AdoptOpenJDK)(build 25.242-b08, mixed mode)
• Visual Studio Code version:
  Version: 1.43.1 (system setup)
  Commit: fe22a9645b44368865c0ba92e2fb881ff1afce94
  Date: 2020-03-18T07:01:20.184Z
  Electron: 7.1.11
  Chrome: 78.0.3904.130
  Node.js: 12.8.1
  V8: 7.8.279.23-electron.0
  OS: Windows_NT x64 10.0.17763
• Java extension version: 0.58.0 (March 5th, 2020)
• Java Debugger extension version: 0.25.1 - 2020-03-06

Steps To Reproduce

1. [step 1]
   Set a conditional breakpoint with string condition
2. [step 2]
   Debug and wait to stop at breakpoint

[attach a sample project reproducing the error]
attach logs

[Warn - 10:32:00] 20-Mar-2020 10:32:00 Failed to destory launch files, will retry again.
[Error - 10:32:11] 20-Mar-2020 10:32:11 [ConditionalBreakpoint]:

org.eclipse.debug.core.DebugException:
at org.eclipse.jdt.internal.debug.eval.ast.engine.ASTEvaluationEngine$EvalRunnable.run(ASTEvaluationEngine.java:829)
at org.eclipse.jdt.internal.debug.core.model.JDIThread$ThreadJob.run(JDIThread.java:3641)
at org.eclipse.core.internal.jobs.Worker.run(Worker.java:63)
Caused by: java.util.EmptyStackException
at java.util.Stack.peek(Stack.java:102)
at java.util.Stack.pop(Stack.java:84)
at org.eclipse.jdt.internal.debug.eval.ast.engine.Interpreter.pop(Interpreter.java:165)
at org.eclipse.jdt.internal.debug.eval.ast.instructions.Instruction.pop(Instruction.java:108)
at org.eclipse.jdt.internal.debug.eval.ast.instructions.SendMessage.execute(SendMessage.java:52)
at org.eclipse.jdt.internal.debug.eval.ast.engine.Interpreter.execute(Interpreter.java:69)
at org.eclipse.jdt.internal.debug.eval.ast.engine.ASTEvaluationEngine$EvalRunnable$1EvaluationRunnable.run(ASTEvaluationEngine.java:751)
at org.eclipse.jdt.internal.debug.core.model.JDIThread.runEvaluation(JDIThread.java:849)
at org.eclipse.jdt.internal.debug.eval.ast.engine.ASTEvaluationEngine$EvalRunnable.run(ASTEvaluationEngine.java:804)
... 2 more

[Error - 10:32:11] 20-Mar-2020 10:32:11 [ConditionalBreakpoint]:

org.eclipse.debug.core.DebugException:
at org.eclipse.jdt.internal.debug.eval.ast.engine.ASTEvaluationEngine$EvalRunnable.run(ASTEvaluationEngine.java:829)
at org.eclipse.jdt.internal.debug.core.model.JDIThread$ThreadJob.run(JDIThread.java:3641)
at org.eclipse.core.internal.jobs.Worker.run(Worker.java:63)
Caused by: java.lang.NullPointerException
at org.eclipse.jdt.internal.debug.eval.ast.instructions.Instruction.setLastValue(Instruction.java:48)
at org.eclipse.jdt.internal.debug.eval.ast.instructions.SendMessage.execute(SendMessage.java:71)
at org.eclipse.jdt.internal.debug.eval.ast.engine.Interpreter.execute(Interpreter.java:69)
at org.eclipse.jdt.internal.debug.eval.ast.engine.ASTEvaluationEngine$EvalRunnable$1EvaluationRunnable.run(ASTEvaluationEngine.java:751)
at org.eclipse.jdt.internal.debug.core.model.JDIThread.runEvaluation(JDIThread.java:849)
at org.eclipse.jdt.internal.debug.eval.ast.engine.ASTEvaluationEngine$EvalRunnable.run(ASTEvaluationEngine.java:804)
... 2 more

[Error - 10:32:11] 20-Mar-2020 10:32:11 [ConditionalBreakpoint]:

org.eclipse.debug.core.DebugException:
at org.eclipse.jdt.internal.debug.eval.ast.engine.ASTEvaluationEngine$EvalRunnable.run(ASTEvaluationEngine.java:829)
at org.eclipse.jdt.internal.debug.core.model.JDIThread$ThreadJob.run(JDIThread.java:3641)
at org.eclipse.core.internal.jobs.Worker.run(Worker.java:63)
Caused by: java.lang.NullPointerException
at org.eclipse.jdt.internal.debug.eval.ast.instructions.Instruction.setLastValue(Instruction.java:48)
at org.eclipse.jdt.internal.debug.eval.ast.instructions.SendMessage.execute(SendMessage.java:71)
at org.eclipse.jdt.internal.debug.eval.ast.engine.Interpreter.execute(Interpreter.java:69)
at org.eclipse.jdt.internal.debug.eval.ast.engine.ASTEvaluationEngine$EvalRunnable$1EvaluationRunnable.run(ASTEvaluationEngine.java:751)
at org.eclipse.jdt.internal.debug.core.model.JDIThread.runEvaluation(JDIThread.java:849)
at org.eclipse.jdt.internal.debug.eval.ast.engine.ASTEvaluationEngine$EvalRunnable.run(ASTEvaluationEngine.java:804)
... 2 more

Current Result

Result of breakpoint condition '"something".equals(xRole)' is not a boolean, please correct your expression.

Expected Result

That the condition inside the conditional breakpoint is evaluated correctly.

Additional Informations