Error "value of context key result is null" when adding a new SQL Azure DB agent (4371190)

When adding a new Azure SQL DB agent, the wizard exits and shows an error with red letters:

Value of context key result is null

The logs show messages like these:

script.system:dbwc_azure_installer_api.isFglamReachedLimit - The selected FglAM (fglam-hostname.example.com) has reached its maximum memory capacity of 272.0 MB. In order to configure the selected agents, an additional 64.0 MB are needed

Provision extra JVM heap memory to the FglAM as described in the Deployment Guide.

1. Edit the baseline.jvmargs.config file located under the [FglAM_HOME]/state/default/config directory
2. Add the new JVM size using available vmparameter.N properties (see example under these steps)
3. Delete the deployments subdirectory
4. Stop the FglAM service/daemon and start it up again

# Parameters for increasing the baseline JVM heap size to 7GB
# 7GB is the recommended baseline JVM heap size for <50 agents using SQL PI
vmparameter.0 = "-Xms7g";
vmparameter.1 = "-Xmx7g";