Ah, why is there a bug in my program?
Japt, 4 bytes
Challenge: Output with the same length as the code
BUG³

Test it
Explanation
B, U, and G are variables for 11, the input, and 16 respectively.
When applied to a number, ³ brings it to the third power.
In Japt, only the last expression is outputted, so only \$16^3 = 4096\$ is outputted, which is the same length as the code (4).
Since B and U are ignored, removing them have no effect on the output. However, their removal changes the length of the program, making it invalid. Removing G raises either the input (U) or 11 (B) to the third power. While \$11^3 = 1331\$ is 4 bytes, the program B³ is only two bytes, making the output invalid. The variable U defaults to 0 when there is no input given, and \$0^3 = 0\$, which is only one byte long.