Externs_0:12 (JSC_NAME_REFERENCE_IN_EXTERNS)
accessing name window in externs has no effect. Perhaps you forgot to add a var keyword?
window['googletag'] = googletag;
^

Externs_0:12 (JSC_NAME_REFERENCE_IN_EXTERNS)
accessing name googletag in externs has no effect. Perhaps you forgot to add a var keyword?
window['googletag'] = googletag;
                      ^

Externs_0:19 (JSC_TYPE_PARSE_ERROR)
Bad type annotation. type annotation incompatible with other annotations. See https://github.com/google/closure-compiler/wiki/Bad-Type-Annotation for more information.
 * @param {Function} cmd command to run when gpt is ready
                     ^

Externs_0:20 (JSC_TYPE_PARSE_ERROR)
Bad type annotation. type annotation incompatible with other annotations. See https://github.com/google/closure-compiler/wiki/Bad-Type-Annotation for more information.
 * @return {Number} size of the array
   ^

Externs_0:26 (JSC_TYPE_PARSE_ERROR)
Bad type annotation. type annotation incompatible with other annotations. See https://github.com/google/closure-compiler/wiki/Bad-Type-Annotation for more information.
 * @return {googletag.PubAdsService}
   ^

Externs_0:28 (JSC_INEXISTENT_PROPERTY)
Property proptype never defined on googletag
googletag.proptype.pubads = function() {};
          ^

Externs_0:31 (JSC_INEXISTENT_PROPERTY)
Property proptype never defined on googletag
googletag.proptype.enableServices = function() {};
          ^

Externs_0:35 (JSC_TYPE_PARSE_ERROR)
Bad type annotation. type annotation incompatible with other annotations. See https://github.com/google/closure-compiler/wiki/Bad-Type-Annotation for more information.
 * @param {string} adunitPath
                   ^

Externs_0:36 (JSC_TYPE_PARSE_ERROR)
Bad type annotation. type annotation incompatible with other annotations. See https://github.com/google/closure-compiler/wiki/Bad-Type-Annotation for more information.
 * @param {Object} size
                   ^

Externs_0:37 (JSC_TYPE_PARSE_ERROR)
Bad type annotation. type annotation incompatible with other annotations. See https://github.com/google/closure-compiler/wiki/Bad-Type-Annotation for more information.
 * @param {string=} opt_div
                    ^

Externs_0:38 (JSC_TYPE_PARSE_ERROR)
Bad type annotation. type annotation incompatible with other annotations. See https://github.com/google/closure-compiler/wiki/Bad-Type-Annotation for more information.
 * @return {googletag.Slot}
   ^

Externs_0:44 (JSC_BAD_JSDOC_ANNOTATION)
Parse error. illegal use of unknown JSDoc tag "construct"; ignoring it
 * @construct
   ^

Externs_0:46 (JSC_CONSTRUCTOR_REQUIRED)
@struct used without @constructor for googletag.PubAdsService
googletag.PubAdsService = function() {};
                          ^

Externs_0:50 (JSC_TYPE_PARSE_ERROR)
Bad type annotation. type annotation incompatible with other annotations. See https://github.com/google/closure-compiler/wiki/Bad-Type-Annotation for more information.
 * @return {googletag.PubAdsService}
   ^

Externs_0:56 (JSC_TYPE_PARSE_ERROR)
Bad type annotation. type annotation incompatible with other annotations. See https://github.com/google/closure-compiler/wiki/Bad-Type-Annotation for more information.
 * @return {googletag.PubAdsService}
   ^

Externs_0:62 (JSC_TYPE_PARSE_ERROR)
Bad type annotation. type annotation incompatible with other annotations. See https://github.com/google/closure-compiler/wiki/Bad-Type-Annotation for more information.
 * @param {string} eventType
                   ^

Externs_0:63 (JSC_TYPE_PARSE_ERROR)
Bad type annotation. type annotation incompatible with other annotations. See https://github.com/google/closure-compiler/wiki/Bad-Type-Annotation for more information.
 * @param {Function} listener
                     ^

Externs_0:64 (JSC_TYPE_PARSE_ERROR)
Bad type annotation. type annotation incompatible with other annotations. See https://github.com/google/closure-compiler/wiki/Bad-Type-Annotation for more information.
 * @return {googletag.PubAdsService}
   ^

Externs_0:76 (JSC_TYPE_PARSE_ERROR)
Bad type annotation. type annotation incompatible with other annotations. See https://github.com/google/closure-compiler/wiki/Bad-Type-Annotation for more information.
 * @param {googletag.PubAdsService} service
                                    ^

Externs_0:77 (JSC_TYPE_PARSE_ERROR)
Bad type annotation. type annotation incompatible with other annotations. See https://github.com/google/closure-compiler/wiki/Bad-Type-Annotation for more information.
 * @return {googletag.Slot}
   ^

Externs_0:83 (JSC_TYPE_PARSE_ERROR)
Bad type annotation. type annotation incompatible with other annotations. See https://github.com/google/closure-compiler/wiki/Bad-Type-Annotation for more information.
 * @return {string}
   ^

Externs_0:94 (JSC_ILLEGAL_PROPERTY_ACCESS)
Cannot do '.' access on a dict
googletag.events.SlotRenderEndedEvent = {};
                 ^

Externs_0:97 (JSC_TYPE_MISMATCH)
assignment
found   : {}
required: (googletag.Slot|null)
googletag.events.SlotRenderEndedEvent.slot = {};
^

Externs_0:97 (JSC_ILLEGAL_PROPERTY_ACCESS)
Cannot do '.' access on a dict
googletag.events.SlotRenderEndedEvent.slot = {};
                 ^

Externs_0:97 (JSC_ILLEGAL_PROPERTY_CREATION)
Cannot add a property to a struct instance after it is constructed. (If you already declared the property, make sure to give it a type.)
googletag.events.SlotRenderEndedEvent.slot = {};
                                      ^

index.js:2 (JSC_INEXISTENT_PROPERTY)
Property pubads never defined on googletag
    googletag.pubads().addEventListener('slotRenderEnded', e => {
              ^

index.js:3 (JSC_UNRECOGNIZED_TYPE_ERROR)
Bad type annotation. Unknown type googletag.events.SlotRenderEndedEvent
      /** @type {googletag.events.SlotRenderEndedEvent} */
                 ^

index.js:15 (JSC_POSSIBLE_INEXISTENT_PROPERTY)
Property publish never defined on pubsub
      pubsub.publish(LOAD_ADTYPE.replace('<adtype>', format), {