Merge branch 'multipart-nextpart-error' into 'master'

Catch _all_ multipart NextPart() errors

Closes #89

See merge request !108

internal/upload/rewrite.go

@@ -87,9 +87,12 @@ func rewriteFormFilesFromMultipart(r *http.Request, writer *multipart.Writer, te
 
 	for {
 		p, err := reader.NextPart()
+		if err != nil {
 			if err == io.EOF {
 				break
 			}
+			return cleanup, err
+		}
 
 		name := p.FormName()
 		if name == "" {
@@ -108,6 +111,7 @@ func rewriteFormFilesFromMultipart(r *http.Request, writer *multipart.Writer, te
 			return cleanup, err
 		}
 	}
+
 	return cleanup, nil
 }