BJT - Influence of increasing \$V_CE\$ on \$I_c\$
Suppose the OpAmp has gain of 1 Million. Any fluctuation of voltage across Rsense ---- the 2 ohms ---- is used in negative feedback to adjust the bipolar's base voltage in the direction needed and by amount needed, to keep the voltage across the 2 ohms at almost exactly the voltage on OpAmp Vin+.

If a 0.1 volt change in Vbase_emitter is needed, the input differential voltage (Vin+ - Vin-) need only change 100 nanoVolts.