Execute failures don't break connection

connection.go

@@ -142,7 +142,9 @@ func (c *Connection) SelectFunc(sql string, onDataRow func(*DataRowReader) error
 			case commandComplete:
 			case bindComplete:
 			default:
-				err = c.processContextFreeMsg(t, r)
+				if e := c.processContextFreeMsg(t, r); e != nil && err == nil {
+					err = e
+				}
 			}
 		} else {
 			return rxErr
@@ -406,9 +408,7 @@ func (c *Connection) Execute(sql string, arguments ...interface{}) (commandTag s
 	}
 
 	for {
-		var t byte
-		var r *MessageReader
-		if t, r, err = c.rxMsg(); err == nil {
+		if t, r, rxErr := c.rxMsg(); rxErr == nil {
 			switch t {
 			case readyForQuery:
 				return
@@ -418,12 +418,12 @@ func (c *Connection) Execute(sql string, arguments ...interface{}) (commandTag s
 			case commandComplete:
 				commandTag = r.ReadString()
 			default:
-				if err = c.processContextFreeMsg(t, r); err != nil {
-					return
+				if e := c.processContextFreeMsg(t, r); e != nil && err == nil {
+					err = e
 				}
 			}
 		} else {
-			return
+			return "", rxErr
 		}
 	}
 }

connection_test.go

@@ -179,7 +179,22 @@ func TestExecute(t *testing.T) {
 	if results != "SELECT 1" {
 		t.Errorf("Unexpected results from Execute: %v", results)
 	}
+}
 
+func TestExecuteFailure(t *testing.T) {
+	conn, err := Connect(*defaultConnectionParameters)
+	if err != nil {
+		t.Fatalf("Unable to establish connection: %v", err)
+	}
+	defer conn.Close()
+
+	if _, err := conn.Execute("select;"); err == nil {
+		t.Fatal("Expected SQL syntax error")
+	}
+
+	if _, err := conn.SelectValue("select 1"); err != nil {
+		t.Fatalf("Execute failure appears to have broken connection: %v", err)
+	}
 }
 
 func TestSelectFunc(t *testing.T) {
@@ -204,6 +219,23 @@ func TestSelectFunc(t *testing.T) {
 	}
 }
 
+func TestSelectFuncFailure(t *testing.T) {
+	conn, err := Connect(*defaultConnectionParameters)
+	if err != nil {
+		t.Fatalf("Unable to establish connection: %v", err)
+	}
+	defer conn.Close()
+
+	// using SelectValue as it delegates to SelectFunc and is easier to work with
+	if _, err := conn.SelectValue("select;"); err == nil {
+		t.Fatal("Expected SQL syntax error")
+	}
+
+	if _, err := conn.SelectValue("select 1"); err != nil {
+		t.Fatalf("SelectFunc failure appears to have broken connection: %v", err)
+	}
+}
+
 func TestSelectRows(t *testing.T) {
 	conn := getSharedConnection()