Error handling

## Error handling |
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| If the JRE search sequence of the installer selects a damaged JRE, the installer might fail to start up correctly. The next time the installer is executed, the installer will ask the user whether the automatic search should be performed again or if a JRE should be manually located or downloaded. If the user chooses manual location or download, the same dialog will be displayed as for in the failure to find a JRE. The download option is only available if a JRE has been dynamically bundled in the "Bundled JRE" step of the media file wizard. A JRE that has been located or downloaded in this way will also be used by your installed application.

| On Windows, when an installer is executed it always generates a log file in the temp directory that contains information about the JRE search sequence and can be used for debugging purposes. The name of the log file starts with `i4j_nlog_`. If you have a problem with JRE detection or the installer startup, please send this log file along with your support request. It is also possible to generate this log for the JRE detection of the generated Windows launchers. In order to switch on logging, please define the environment variable `INSTALL4J_LOG=yes` and look for the newest text file whose name starts with `i4j_nlog_` in the temp directory.

| The process of an installers returns `0` if the installation was completed successfully, `1` if the installation fails and `83` if the installer could not find a suitable JVM to run. These exit codes are especially useful to check the result of an unattended installer run.