Unexpected Internal Error: NullPointerException

[YuanchengJiang]

Describe the bug

Some queries with join would incur NullPointerException:

2023-05-11T13:12:03.964526Z C i.q.c.p.PGWireServer internal error [ex=
java.lang.NullPointerException: Cannot invoke "io.questdb.griffin.SqlExecutionContext.getNow()" because "this.context" is null
	at io.questdb.griffin.engine.functions.date.NowFunctionFactory$Func.getTimestamp(NowFunctionFactory.java:62)
	at io.questdb.griffin.engine.functions.lt.LtTimestampFunctionFactory$LtTimestampFunction.getBool(LtTimestampFunctionFactory.java:67)
	at io.questdb.griffin.SqlCodeGenerator.generateJoins(SqlCodeGenerator.java:1750)
	at io.questdb.griffin.SqlCodeGenerator.generateSelect(SqlCodeGenerator.java:2676)
	at io.questdb.griffin.SqlCodeGenerator.generateQuery0(SqlCodeGenerator.java:2272)
	at io.questdb.griffin.SqlCodeGenerator.generateQuery(SqlCodeGenerator.java:2259)
	at io.questdb.griffin.SqlCodeGenerator.generateSubQuery(SqlCodeGenerator.java:3620)
	at io.questdb.griffin.SqlCodeGenerator.generateSelectGroupBy(SqlCodeGenerator.java:3114)
	at io.questdb.griffin.SqlCodeGenerator.generateSelect(SqlCodeGenerator.java:2665)
	at io.questdb.griffin.SqlCodeGenerator.generateQuery0(SqlCodeGenerator.java:2272)
	at io.questdb.griffin.SqlCodeGenerator.generateQuery(SqlCodeGenerator.java:2259)
	at io.questdb.griffin.SqlCodeGenerator.generate(SqlCodeGenerator.java:186)
	at io.questdb.griffin.SqlCompiler.generate(SqlCompiler.java:2731)
	at io.questdb.griffin.SqlCompiler.compileUsingModel(SqlCompiler.java:1322)
	at io.questdb.griffin.SqlCompiler.compileInner(SqlCompiler.java:1271)
	at io.questdb.griffin.SqlCompiler.compileBatch(SqlCompiler.java:322)
	at io.questdb.cutlass.pgwire.PGConnectionContext.processQuery(PGConnectionContext.java:2413)
	at io.questdb.cutlass.pgwire.PGConnectionContext.parse(PGConnectionContext.java:1683)
	at io.questdb.cutlass.pgwire.PGConnectionContext.handleClientOperation(PGConnectionContext.java:418)
	at io.questdb.cutlass.pgwire.PGJobContext.handleClientOperation(PGJobContext.java:89)
	at io.questdb.cutlass.pgwire.PGWireServer$1.lambda$$0(PGWireServer.java:91)
	at io.questdb.network.AbstractIODispatcher.processIOQueue(AbstractIODispatcher.java:189)
	at io.questdb.cutlass.pgwire.PGWireServer$1.run(PGWireServer.java:128)
	at io.questdb.mp.Worker.run(Worker.java:118)
]

To reproduce

The following query works with the system table telemetry to reproduce the error:

select count(*) from telemetry as a inner join telemetry as b on a.event=b.event where now()=now();

Expected Behavior

No response

Environment

- **QuestDB version**: 7.1.1
- **OS**: ubuntu 20.04
- **Browser**:

Additional context

No response

[Rbcoder1]

I want to work on it