Index error during Topsar-Split while computing IW1-2-3 coherence via Snappy

I had a working code for coherence but now it does not work and returns

RuntimeError: org.esa.snap.core.gpf.OperatorException: Index: 0, Size: 0

The inputs are 2-3 (depends on the DOY) S1 SLC product on the same relative orbit. I have separated functions for all IWs.

def topsar_split_1(product):
HashMap = jpy.get_type(‘java.util.HashMap’)
parameters = HashMap()
parameters.put(“subswath”, “IW1”)
parameters.put(“selectedPolarisations”, “VV”)
parameters.put(“firstBurstIndex”, “1”)
parameters.put(“lastBurstIndex”, “9”)
parameters.put(“wktAoi”, None)
return GPF.createProduct(“TOPSAR-Split”, parameters, product)