Electrical – Current flowing in a short circuit with a voltage source

I want to calculate the current flowing in the node A of the following circuit:

^{simulate this circuit – Schematic created using CircuitLab}

This can be approached in several ways.

1. The tension in a short circuit is 0 but what about the current ? By Ohm's law \$I = {V \over R} \$ if R approach 0 and \$V > 0\$ then I approach infinity. If \$V = 0\$ as in a short circuit then this lead to \${0\over 0}\$. Both forms has no meaning in mathematics and are undefined.

2. From the parallel resistors formuala, a resistor in parallel with a short circuit is equivalent to a short circuit. So if the entire circuit is equivalent to a shorted voltage source. The voltage provided by the source is \$V > 0\$ but in a short circuit \$V = 0\$. So again an undefined rational number.

3. By KCL the sum of the currents in node B must be 0. Maybe we can consider V1 and R1 in series if the short circuit is ignored. If that's the case the sum of the currents is something like \$I – I + I_s = 0 \Rightarrow I_s = 0 \$. Is it a valid reasoning ?

How can I solve this problem ?