The programming seems to be fine (no bugs so far), though you might want to make a few changes for playability. Just a few suggestions:
-have enemies spawn from off-screen at the beginning of the level; there's almost no way to avoid a few initial collisions.
-adjust the damage or program auto-fire; mashing the space bar this much simply isn't feasible.
-enemy movement is too fast; slowing it down a bit allows players time to establish patterns and escape routes, but at its current speed, it's far too dependent on luck.
On the technical side of things, you might want to address the player character's tendency to start spinning when it reaches the mouse; you could perhaps program it to stop seeking when the mouse is over the player character.