dbt run: Trips when invoked twice

[amotl]

Problem

When invoking dbt run twice on the delete+insert materialization example project added per crate/cratedb-examples#784, it errors out.

Error output

23:14:04  1 of 1 START sql incremental model doc.test .................................... [RUN]
23:14:04  1 of 1 ERROR creating sql incremental model doc.test ........................... [ERROR in 0.42s]
23:14:05
23:14:05  Finished running 1 incremental model in 0 hours 0 minutes and 0.56 seconds (0.56s).
23:14:05
23:14:05  Completed with 1 error, 0 partial successes, and 0 warnings:
23:14:05
23:14:05    Database Error in model test (models/example/test.sql)
  Column classification['type'] unknown
  CONTEXT:  io.crate.metadata.doc.DocTableInfo.getDynamic(DocTableInfo.java:684)
  io.crate.metadata.doc.DocTableInfo.resolveColumn(DocTableInfo.java:710)
  io.crate.analyze.InsertAnalyzer.lambda$analyze$0(InsertAnalyzer.java:125)
  java.base/java.util.stream.ReferencePipeline$3$1.accept(ReferencePipeline.java:215)
  java.base/java.util.ArrayList$ArrayListSpliterator.forEachRemaining(ArrayList.java:1709)
  java.base/java.util.stream.AbstractPipeline.copyInto(AbstractPipeline.java:570)
  java.base/java.util.stream.AbstractPipeline.wrapAndCopyInto(AbstractPipeline.java:560)
  java.base/java.util.stream.AbstractPipeline.evaluate(AbstractPipeline.java:636)
  java.base/java.util.stream.AbstractPipeline.evaluateToArrayNode(AbstractPipeline.java:291)
  java.base/java.util.stream.ReferencePipeline.toArray(ReferencePipeline.java:656)
  java.base/java.util.stream.ReferencePipeline.toArray(ReferencePipeline.java:662)
  java.base/java.util.stream.ReferencePipeline.toList(ReferencePipeline.java:667)
  io.crate.analyze.InsertAnalyzer.analyze(InsertAnalyzer.java:126)
  io.crate.analyze.Analyzer$AnalyzerDispatcher.visitInsert(Analyzer.java:543)
  io.crate.analyze.Analyzer$AnalyzerDispatcher.visitInsert(Analyzer.java:261)
  io.crate.sql.tree.Insert.accept(Insert.java:102)
  io.crate.analyze.Analyzer.analyze(Analyzer.java:243)
  io.crate.session.Session.analyze(Session.java:362)
  io.crate.protocols.postgres.PostgresWireProtocol.handleSingleQuery(PostgresWireProtocol.java:823)
  io.crate.protocols.postgres.PostgresWireProtocol.lambda$handleSimpleQuery$6(PostgresWireProtocol.java:809)
  compiled code at target/run/testdrive_materialized/models/example/test.sql
23:14:05
23:14:05  Done. PASS=0 WARN=0 ERROR=1 SKIP=0 TOTAL=1