Runtime error: nil pointer dereference in StartNormalize activity on PostgresConnector

[seonghobae]

Description:
When running the StartNormalize activity in the PeerDB project (using the PostgresConnector), we encountered a runtime error due to a nil pointer dereference. This issue occurred repeatedly during normalization steps and appears to originate from normalize_stmt_generator.go and postgres.go within the Postgres connector logic.

Steps to Reproduce:

1. Run a workflow that triggers the StartNormalize activity in a Temporal setup.
2. Observe the workflow execution logs during the normalization phase.
3. The error runtime error: invalid memory address or nil pointer dereference appears consistently, halting the normalization process.

Expected Behavior:
The StartNormalize activity should execute successfully, generating all necessary normalization statements and completing without runtime panics.

Actual Behavior:
The workflow fails at the StartNormalize activity with a panic caused by a nil pointer dereference. The provided stack trace shows that generateFallbackStatements in normalize_stmt_generator.go:80 attempts to access an uninitialized object.

Relevant Logs (Redacted for Security):

{"time":"2024-12-13T08:04:03Z","level":"ERROR","msg":"Activity panic.","ActivityType":"StartNormalize","PanicError":"runtime error: invalid memory address or nil pointer dereference","PanicStack":".../normalize_stmt_generator.go:80 +0x3d ..."}

Additional Context:

• Ensuring that all structs and pointers are properly initialized before usage may prevent this error.
• Adding defensive checks for nil before dereferencing objects in generateNormalizeStatements or generateFallbackStatements could be a potential fix.
• It might be helpful to add logging or assertions around these code paths to identify uninitialized states earlier.

[serprex]

Looks like same thing as #2317 will need to replicate fix beyond snowflake