[fix) treat the case nbCores <= 0

app/modules/prover/index.ts

@@ -23,6 +23,8 @@ export const ProverDependency = {
         }
         if (conf.nbCores === null || conf.nbCores === undefined) {
           conf.nbCores = Math.min(Constants.CORES_MAXIMUM_USE_IN_PARALLEL, require('os').cpus().length)
+        } else if (conf.nbCores <= 0) {
+          conf.nbCores = 1
         }
         if (conf.prefix === null || conf.prefix === undefined) {
           conf.prefix = Constants.DEFAULT_PEER_ID;