Comment 1 for bug 720699

Could you check the current settings for the paint bucket tool in its controls bar right above the canvas:
What is the current value for 'Grow/Shrink by:'?
Does it still crash if you reset the options to default values (using the last button on the controls bar)?

Possibly related:
Bug #587769 “Paint Bucket: Upper/lower value in context menu of Glow/shrink are unrealistic”