If mapstruct is unable to map a property, in version 1.3.1.Final it reports:

"Can't map property "[...]" to "[...]". Consider to declare/implement a mapping method: "[...]".

Since version 1.4.0.Final however a big and less helpful stacktrace is reported instead:

/mapstruct-demo/src/main/java/org/example/DemoMapper.java:[6,8] Internal error in the mapping processor: java.lang.IndexOutOfBoundsException: Index: 0, Size: 0
at java.util.ArrayList.rangeCheck(ArrayList.java:653)
at java.util.ArrayList.get(ArrayList.java:429)
at org.mapstruct.ap.internal.model.common.Type$TypeVarMatcher.visitDeclared(Type.java:1165)
at org.mapstruct.ap.internal.model.common.Type$TypeVarMatcher.visitDeclared(Type.java:1141)
at com.sun.tools.javac.code.Type$ClassType.accept(Type.java:936)
at javax.lang.model.util.AbstractTypeVisitor6.visit(AbstractTypeVisitor6.java:92)
at org.mapstruct.ap.internal.model.common.Type.resolveTypeVarToType(Type.java:1136)
at org.mapstruct.ap.internal.model.source.builtin.BuiltInMethod.matches(BuiltInMethod.java:70)
at org.mapstruct.ap.internal.model.source.selector.TypeSelector.lambda$getMatchingParameterBinding$0(TypeSelector.java:158)
at org.mapstruct.ap.internal.model.source.selector.TypeSelector$$Lambda$82/14814827.test(Unknown Source)
at java.util.ArrayList.removeIf(ArrayList.java:1405)
at org.mapstruct.ap.internal.model.source.selector.TypeSelector.getMatchingParameterBinding(TypeSelector.java:157)
at org.mapstruct.ap.internal.model.source.selector.TypeSelector.getMatchingMethods(TypeSelector.java:71)
at org.mapstruct.ap.internal.model.source.selector.MethodSelectors.getMatchingMethods(MethodSelectors.java:62)
at org.mapstruct.ap.internal.processor.creation.MappingResolverImpl$ResolvingAttempt.getBestMatch(MappingResolverImpl.java:452)
at org.mapstruct.ap.internal.processor.creation.MappingResolverImpl$ResolvingAttempt.getTargetAssignment(MappingResolverImpl.java:263)
at org.mapstruct.ap.internal.processor.creation.MappingResolverImpl$ResolvingAttempt.access$100(MappingResolverImpl.java:158)
at org.mapstruct.ap.internal.processor.creation.MappingResolverImpl.getTargetAssignment(MappingResolverImpl.java:139)
at org.mapstruct.ap.internal.model.PropertyMapping$PropertyMappingBuilder.build(PropertyMapping.java:243)
at org.mapstruct.ap.internal.model.BeanMappingMethod$Builder.applyPropertyNameBasedMapping(BeanMappingMethod.java:1236)
at org.mapstruct.ap.internal.model.BeanMappingMethod$Builder.applyPropertyNameBasedMapping(BeanMappingMethod.java:1200)
at org.mapstruct.ap.internal.model.BeanMappingMethod$Builder.build(BeanMappingMethod.java:269)
at org.mapstruct.ap.internal.processor.MapperCreationProcessor.getMappingMethods(MapperCreationProcessor.java:378)
at org.mapstruct.ap.internal.processor.MapperCreationProcessor.getMapper(MapperCreationProcessor.java:152)
at org.mapstruct.ap.internal.processor.MapperCreationProcessor.process(MapperCreationProcessor.java:123)
at org.mapstruct.ap.internal.processor.MapperCreationProcessor.process(MapperCreationProcessor.java:74)
at org.mapstruct.ap.MappingProcessor.process(MappingProcessor.java:338)
at org.mapstruct.ap.MappingProcessor.processMapperTypeElement(MappingProcessor.java:318)
at org.mapstruct.ap.MappingProcessor.processMapperElements(MappingProcessor.java:267)
at org.mapstruct.ap.MappingProcessor.process(MappingProcessor.java:166)
at com.sun.tools.javac.processing.JavacProcessingEnvironment.callProcessor(JavacProcessingEnvironment.java:794)
at com.sun.tools.javac.processing.JavacProcessingEnvironment.discoverAndRunProcs(JavacProcessingEnvironment.java:705)
at com.sun.tools.javac.processing.JavacProcessingEnvironment.access$1800(JavacProcessingEnvironment.java:91)
at com.sun.tools.javac.processing.JavacProcessingEnvironment$Round.run(JavacProcessingEnvironment.java:1035)
at com.sun.tools.javac.processing.JavacProcessingEnvironment.doProcessing(JavacProcessingEnvironment.java:1176)
at com.sun.tools.javac.main.JavaCompiler.processAnnotations(JavaCompiler.java:1170)
at com.sun.tools.javac.main.JavaCompiler.compile(JavaCompiler.java:856)
at com.sun.tools.javac.main.Main.compile(Main.java:523)
at com.sun.tools.javac.api.JavacTaskImpl.doCall(JavacTaskImpl.java:129)
at com.sun.tools.javac.api.JavacTaskImpl.call(JavacTaskImpl.java:138)
at org.codehaus.plexus.compiler.javac.JavaxToolsCompiler.compileInProcess(JavaxToolsCompiler.java:126)
at org.codehaus.plexus.compiler.javac.JavacCompiler.performCompile(JavacCompiler.java:174)
at org.apache.maven.plugin.compiler.AbstractCompilerMojo.execute(AbstractCompilerMojo.java:1134)
at org.apache.maven.plugin.compiler.CompilerMojo.execute(CompilerMojo.java:187)
at org.apache.maven.plugin.DefaultBuildPluginManager.executeMojo(DefaultBuildPluginManager.java:137)
at org.apache.maven.lifecycle.internal.MojoExecutor.execute(MojoExecutor.java:210)
at org.apache.maven.lifecycle.internal.MojoExecutor.execute(MojoExecutor.java:156)
at org.apache.maven.lifecycle.internal.MojoExecutor.execute(MojoExecutor.java:148)
at org.apache.maven.lifecycle.internal.LifecycleModuleBuilder.buildProject(LifecycleModuleBuilder.java:117)
at org.apache.maven.lifecycle.internal.LifecycleModuleBuilder.buildProject(LifecycleModuleBuilder.java:81)
at org.apache.maven.lifecycle.internal.builder.singlethreaded.SingleThreadedBuilder.build(SingleThreadedBuilder.java:56)
at org.apache.maven.lifecycle.internal.LifecycleStarter.execute(LifecycleStarter.java:128)
at org.apache.maven.DefaultMaven.doExecute(DefaultMaven.java:305)
at org.apache.maven.DefaultMaven.doExecute(DefaultMaven.java:192)
at org.apache.maven.DefaultMaven.execute(DefaultMaven.java:105)
at org.apache.maven.cli.MavenCli.execute(MavenCli.java:957)
at org.apache.maven.cli.MavenCli.doMain(MavenCli.java:289)
at org.apache.maven.cli.MavenCli.main(MavenCli.java:193)
at sun.reflect.NativeMethodAccessorImpl.invoke0(Native Method)
at sun.reflect.NativeMethodAccessorImpl.invoke(NativeMethodAccessorImpl.java:62)
at sun.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAccessorImpl.java:43)
at java.lang.reflect.Method.invoke(Method.java:497)
at org.codehaus.plexus.classworlds.launcher.Launcher.launchEnhanced(Launcher.java:282)
at org.codehaus.plexus.classworlds.launcher.Launcher.launch(Launcher.java:225)
at org.codehaus.plexus.classworlds.launcher.Launcher.mainWithExitCode(Launcher.java:406)
at org.codehaus.plexus.classworlds.launcher.Launcher.main(Launcher.java:347)

I guess the previous behaviour is preferable.

For reference I uploaded a demo project that generates the shown stack trace to https://github.com/martin-mfg/mapstruct-demo. Simply run mvn clean package there.