Poly sources are not directly supported by the Eeschema GSOURCE symbol.
The ngspice netlist does show G1 CurrentOut 0 POLY (1) 3 0 0.1 1.0 2.0
which you have typed in manually (Sim.Params field).
As the manual states, the tokens 3 0 are nodes of a controlling source. But in your netlist node 3 is not connected to anything. So it is an open node, which leads to ngspice bailing out during simulation. With the RSHUNT option node 3 of the netlist will be connected to 0 by a resistor. Then the simulation runs, but with 0 V as controlling voltage.
So you have to figure out what the name of the controlling net might be, or you may give it a name by a label. Here is seems to be ‘ControlToO2’. Then you have to type in this name instead of 3, like G1 CurrentOut 0 POLY (1) ControlToO2 0 0.1 1.0 2.0
(not tested)