Is my understanding of how not to use the ($\rightarrow$ Introduction) rule correct?

Question

Prove $ A \vee B, \neg A \vdash B $

1. $A \vee B \quad\quad\quad$ data
2. $\neg A \quad\quad\quad\quad$ data
3. $\neg A \rightarrow B \quad\quad$ $\rightarrow $ Introduction, Subcomputation below

$\quad\quad 3.1 \space \neg A \quad $ Assumption

$\quad\quad \color{red}{3.2} \space B \quad$ from (2)(3), $\rightarrow$ Elimination (Modus Ponens)

Am I correct in saying that line 3.2 is incorrect as you can't use line 3 to prove itself?

Answer 1

From

Yes, 3.2 is incorrect since you cannot use what is to be derived as part of the derivation. - @md2perpe

I can indeed see that 3.2 is not a correct derivation.