[SPARK-5380][GraphX]  Solve an ArrayIndexOutOfBoundsException when build graph with a file format error

When I build a graph with a file format error, there will be an ArrayIndexOutOfBoundsException

Author: Leolh <leosandylh@gmail.com>

Closes #4176 from Leolh/patch-1 and squashes the following commits:

94f6d22 [Leolh] Update GraphLoader.scala
23767f1 [Leolh] [SPARK-3650][GraphX] There will be an ArrayIndexOutOfBoundsException if the format of the source file is wrong