Answer:

mistake

Answer	Crossword Clue
MISTAKE	Case for an eraser?
MISTAKE	Error
MISTAKE	Clinker

MISTAKE	Goof
MISTAKE	"Oopsy!" evoker
MISTAKE	"Happy accident," so to speak
MISTAKE	Boo-boo
MISTAKE	"Oops!" prompter
MISTAKE	Oversight
MISTAKE	Foul-up
MISTAKE	Howler

MISTAKE	Source of learning?
MISTAKE	Slip
MISTAKE	Slip.
MISTAKE	Jupiter's is corrected: Poe's Gold Bug.
MISTAKE	Alice makes one after another in Wonderland.
MISTAKE	A wrong definition, for instance.
MISTAKE	Estimate incorrectly.
MISTAKE	Example of fallibility.

MISTAKE	Eraser's target
MISTAKE	Slipup
MISTAKE	Blunder
MISTAKE	Gaffe
MISTAKE	"Man is Nature's sole ...!": Gilbert
MISTAKE	Example of fallibility
MISTAKE	Boner
MISTAKE	It may be costly

MISTAKE	Foozle
MISTAKE	Slip-up
MISTAKE	An "X" may signify one