fixing setting a breakpoint in an invalid IL offset

src/mono/wasm/debugger/BrowserDebugProxy/MonoProxy.cs

@@ -1721,6 +1721,9 @@ private async Task<bool> OnSetNextIP(MessageId sessionId, SourceLocation targetL
                 return false;
 
             var breakpointId = await context.SdbAgent.SetBreakpoint(scope.Method.DebugId, ilOffset.Offset, token);
+            if (breakpointId == -1)
+                return false;
+
             context.TempBreakpointForSetNextIP = breakpointId;
             await SendResume(sessionId, token);
             return true;

src/mono/wasm/debugger/BrowserDebugProxy/MonoSDBHelper.cs

@@ -1359,7 +1359,9 @@ public async Task<int> SetBreakpoint(int methodId, long il_offset, CancellationT
             commandParamsWriter.Write((byte)ModifierKind.LocationOnly);
             commandParamsWriter.Write(methodId);
             commandParamsWriter.Write(il_offset);
-            using var retDebuggerCmdReader = await SendDebuggerAgentCommand(CmdEventRequest.Set, commandParamsWriter, token);
+            using var retDebuggerCmdReader = await SendDebuggerAgentCommand(CmdEventRequest.Set, commandParamsWriter, token, false);
+            if (retDebuggerCmdReader.HasError)
+                return -1;
             return retDebuggerCmdReader.ReadInt32();
         }