Javascript 无法读取属性'；拆分'；在NgbTooltip上未定义的值-@ng bootstrap/ng bootstrap

当悬停从@ng bootstrap/ng bootstrap使用NgbTooltip创建的工具提示时，我收到一个错误，表示无法读取未定义的属性“split”。调试时，我看到placement值被接收为“undefined”，当我检查html时，代码看起来不错，我正在传递[placement]属性的值

控制台中的错误：

EXCEPTION: Cannot read property 'split' of undefined
ErrorHandler.handleError @ error_handler.js:54
next @ application_ref.js:348
schedulerFn @ async.js:93
SafeSubscriber.__tryOrUnsub @ Subscriber.js:236
SafeSubscriber.next @ Subscriber.js:185
Subscriber._next @ Subscriber.js:125
Subscriber.next @ Subscriber.js:89
Subject.next @ Subject.js:55
EventEmitter.emit @ async.js:79
NgZone.triggerError @ ng_zone.js:333
onHandleError @ ng_zone.js:294
ZoneDelegate.handleError @ zone.js:338
Zone.runTask @ zone.js:169
ZoneTask.invoke @ zone.js:420
error_handler.js:59 ORIGINAL STACKTRACE:
ErrorHandler.handleError @ error_handler.js:59
next @ application_ref.js:348
schedulerFn @ async.js:93
SafeSubscriber.__tryOrUnsub @ Subscriber.js:236
SafeSubscriber.next @ Subscriber.js:185
Subscriber._next @ Subscriber.js:125
Subscriber.next @ Subscriber.js:89
Subject.next @ Subject.js:55
EventEmitter.emit @ async.js:79
NgZone.triggerError @ ng_zone.js:333
onHandleError @ ng_zone.js:294
ZoneDelegate.handleError @ zone.js:338
Zone.runTask @ zone.js:169
ZoneTask.invoke @ zone.js:420
error_handler.js:60 TypeError: Cannot read property 'split' of undefined
    at Positioning.positionElements (positioning.js:83)
    at positionElements (positioning.js:129)
    at tooltip.js:47
    at SafeSubscriber.schedulerFn [as _next] (async.js:105)
    at SafeSubscriber.__tryOrUnsub (Subscriber.js:236)
    at SafeSubscriber.next (Subscriber.js:185)
    at Subscriber._next (Subscriber.js:125)
    at Subscriber.next (Subscriber.js:89)
    at EventEmitter.Subject.next (Subject.js:55)
    at EventEmitter.emit (async.js:79)
    at ng_zone.js:244
    at ZoneDelegate.invoke (zone.js:334)
    at Zone.run (zone.js:126)
    at NgZone.runOutsideAngular (ng_zone.js:164)
    at NgZone.checkStable (ng_zone.js:244)

我的HTML代码：

<template #tipContent>{{licenorsTooltip}}</template>
  <button type="button" class="licensor-btn"  [placement]="bottom" [ngbTooltip]="tipContent" #t="ngbTooltip" triggers="manual" 
    (click)="toggleSelect()" on-mouseover='toolTipOver()' on-mouseleave="toolTipLeave()"> </button> 

{{licenorstoltip}

---

请注意，工具提示按预期工作，并且仅在悬停的第一个实例上引发错误。有人能说代码出了什么问题吗？

我通过使用

placement

而不是

[placement]

placement

应该是

string

或者使用

placement=“bottom”

或者

bottom

应该是

string中的
string
属性来删除错误[property]=“bottom”

我通过使用

placement

而不是

[placement]

删除了错误

placement

应该是

string

或者使用

placement=“bottom”

或者

bottom

应该是

[property]=“bottom”

中的

string

属性