Keyword "then" should be a viable input

[jmr2000]

Given this model:

if threat.level == high then {
    perform soundAlarm {in cause = threat;}
} else if threat.level == medium then {
    action sendNotification {in msg = threat;}
} else {
    action beginMonitoring {in target = threat;}
}

We get an error:
[ERROR] StringReader:<16,29>: no viable alternative at input 'ifthreat.level==highthen{', expecting 'requirement', 'connection', 'satisfy', 'connection', '?', 'requirement', 'language', 'satisfy', Name (with additional constraints from connectionUsage), '/', 'return', 'in', 'subject', '-', 'include', 'assign', 'transition', 'use', 'use', 'package', 'readonly', 'assert', 'then', 'assert', 'assert', 'frame', 'assert', 'frame', 'perform', 'allocate', 'allocate', 'verify', 'defined by', 'else', 'verify', 'perform', 'local', 'not', 'join', 'not', 'individual', 'inout', Name (with additional constraints from mCQualifiedName), 'variation', 'message', 'alias', 'interface', 'interface', 'variant', 'part', Name (with additional constraints from anonymousUsage), 'then', Name (with additional constraints from sysMLQualifiedName), 'part', 'send', 'rendering', 'rendering', 'action', 'connection', 'action', 'action', 'allocation', 'action', 'action', 'action', 'action', 'action', 'action', 'action', Name (with additional constraints from bind), 'library', 'redefines', '#', Name (with additional constraints from acceptActionUsage), Name (with additional constraints from inlineAcceptActionUsage), 'decide', Name (with additional constraints from ifActionUsage), 'ref', '@', Name (with additional constraints from allocationUsageParam), Name (with additional constraints from allocationUsageTo), 'abstract', 'flow', Name (with additional constraints from sysMLConditionalSuccession), 'individual', '#', 'require', Name (with additional constraints from sysMLSuccession), 'require', 'allocation', 'dependency', 'require', 'allocation', 'standard', 'allocation', 'flow', 'calc', Name (with additional constraints from forLoopActionUsage), 'calc', Name (with additional constraints from loopActionUsage), 'loop', Name (with additional constraints from whileActionUsage), ':>>', Name (with additional constraints from sendActionUsage), 'analysis', Name (with additional constraints from assignmentActionUsage), 'require', 'analysis', 'for', '<<', 'verification', 'verification', 'assume', 'assume', 'timeslice', 'snapshot', 'assume', 'end', 'view', 'view', 'assume', 'references', 'out', 'first', 'first', 'first', 'derived', 'binding', 'if', 'private', 'filter', 'case', 'if', 'case', 'static', 'accept', 'merge', 'accept', 'occurrence', 'final', 'render', 'occurrence', 'item', 'item', 'timing', 'connect', 'actor', 'subsets', 'event', 'metadata', 'while', 'metadata', 'concern', 'port', 'concern', '[', 'port', 'if', 'viewpoint', 'import', 'viewpoint', ':', 'constraint', 'constraint', 'constraint', 'enum', '[', 'bind', 'enum', 'public', 'rep', 'exhibit', 'exhibit', 'refines', 'succession', 'first', 'stakeholder', 'expose', 'protected', ':>', '::>', 'attribute', 'succession', ':>', '<', 'fork', 'succession', '+', 'attribute', 'state', 'state', 'do' or 'specializes' in rule stack: [SysMLModel, SysMLElement] 
if threat.level == high then {

This should be a valid model but the keyword "then" is not a viable.