proc: in Next return address could be invalid, ignore errors setting it

Updates #893

pkg/proc/threads.go

@@ -250,10 +250,11 @@ func next(dbp Process, stepInto bool) error {
 				// this frame and on the return frame.
 				bp.Cond = sameOrRetFrameCond
 			}
-		} else {
-			return err
 		}
+		// Return address could be wrong, if we are unable to set a breakpoint
+		// there it's ok.
 	}
+
 	if bp, _, _ := curthread.Breakpoint(); bp == nil {
 		curthread.SetCurrentBreakpoint()
 	}

pkg/terminal/command_test.go

@@ -216,7 +216,7 @@ func TestExecuteFile(t *testing.T) {
 
 func TestIssue354(t *testing.T) {
 	printStack([]api.Stackframe{}, "")
-	printStack([]api.Stackframe{{api.Location{PC: 0, File: "irrelevant.go", Line: 10, Function: nil}, nil, nil, 0, nil}}, "")
+	printStack([]api.Stackframe{{api.Location{PC: 0, File: "irrelevant.go", Line: 10, Function: nil}, nil, nil, 0, ""}}, "")
 }
 
 func TestIssue411(t *testing.T) {