No overwriting of global err before return

common/test/client.go

@@ -82,7 +82,9 @@ func (r *Request) Do() (err error) {
 	if err != nil {
 		return err
 	}
-	defer (func() { err = res.Body.Close() })()
+	defer (func() { 
+		if err == nil { err = res.Body.Close() }
+	})()
 
 	if res.StatusCode != r.WantedStatusCode {
 		return fmt.Errorf("incorrect status code. Expected: %d  Got: %d", r.WantedStatusCode, res.StatusCode)

common/test/config.go

@@ -143,7 +143,7 @@ func NewMatrixKey(matrixKeyPath string) (err error) {
 	}
 
 	defer (func() {
-		err = keyOut.Close()
+		if err == nil {err = keyOut.Close()}
 	})()
 
 	err = pem.Encode(keyOut, &pem.Block{

mediaapi/fileutils/fileutils.go

@@ -112,7 +112,10 @@ func WriteTempFile(reqReader io.Reader, maxFileSizeBytes config.FileSizeBytes, a
 	if err != nil {
 		return
 	}
-	defer (func() { err = tmpFile.Close() })()
+	defer (func() {
+		if err == nil {err = tmpFile.Close()
+		} 
+	})()
 
 	// The amount of data read is limited to maxFileSizeBytes. At this point, if there is more data it will be truncated.
 	limitedReader := io.LimitReader(reqReader, int64(maxFileSizeBytes))

roomserver/storage/postgres/invite_table.go

@@ -120,7 +120,9 @@ func (s *inviteStatements) updateInviteRetired(
 	if err != nil {
 		return nil, err
 	}
-	defer (func() { err = rows.Close() })()
+	defer (func() { 
+		if err == nil {err = rows.Close()} 
+	})()
 	for rows.Next() {
 		var inviteEventID string
 		if err := rows.Scan(&inviteEventID); err != nil {