Fixes null point error when the worksheet contains errors

lib.go

@@ -863,6 +863,7 @@ func readSheetsFromZipFile(f *zip.File, file *File, sheetXMLMap map[string]strin
 				sb.WriteString(strconv.Itoa(sheet.Index))
 				sb.WriteString("} ")
 				sb.WriteString(sheet.Error.Error())
+				continue
 			}
 			sheetName := sheet.Sheet.Name
 			sheetsByName[sheetName] = sheet.Sheet

lib_test.go

@@ -1364,6 +1364,13 @@ func TestLib(t *testing.T) {
 		}
 	})
 
+	// Attempting to open a file with an invalid sheet name.
+	csRunO(c, "ReadFileWithInvalidSheet", func(c *qt.C, option FileOption) {
+		_, err := OpenFile("./testdocs/sheet_name_length_above_max.xlsx", option)
+		c.Assert(err, qt.Not(qt.IsNil))
+		c.Assert(err.Error(), qt.Equals, "OpenFile: ReadZip: ReadZipReader: {SheetIndex: 0} readSheetFromFile: sheet name is invalid: sheet name must be 31 or fewer characters long.  It is currently '32' characters long")
+	})
+
 }
 
 func TestReadRowsFromSheet(t *testing.T) {