[BUGFIX] Initialize $currentR in analyseTypoLinks

There are pathes through analyseTypoLinks where currentR is
 not set, it can happen that the fetchType hook gets
called with currentR=null.

This throws an API error as the fetchType interface
requires the first arg to be an array.

Change-Id: I2d517b8c57678e645c590b51d50343c42a3d36a9
Resolves: #30043
Releases: 4.6
Reviewed-on: http://review.typo3.org/5097
Reviewed-by: Georg Ringer
Tested-by: Georg Ringer