UnhandledPromiseRejectionWarning on jsonParser

[evidolob]

Describe the bug

Telemetry reports that error:

[Error - 1:10:47 AM] (node:31445) UnhandledPromiseRejectionWarning: TypeError: sequenceNode.properties is not iterable (cannot read property undefined) 
at /home/_username_/.vscode-server/extensions/redhat.vscode-yaml-0.20.0/node_modules/yaml-language-server/out/server/src/languageservice/parser/jsonParser07.js:917:46
at Array.forEach (<anonymous>) 
at _validateObjectNode (/home/_username_/.vscode-server/extensions/redhat.vscode-yaml-0.20.0/node_modules/yaml-language-server/out/server/src/languageservice/parser/jsonParser07.js:916:57) 
at validate (/home/_username_/.vscode-server/extensions/redhat.vscode-yaml-0.20.0/node_modules/yaml-language-server/out/server/src/languageservice/parser/jsonParser07.js:438:13) 
at _validateObjectNode (/home/_username_/.vscode-server/extensions/redhat.vscode-yaml-0.20.0/node_modules/yaml-language-server/out/server/src/languageservice/parser/jsonParser07.js:983:25) 
at validate (/home/_username_/.vscode-server/extensions/redhat.vscode-yaml-0.20.0/node_modules

Environment

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• Mac
• Linux
• other (please specify)